Lean codes on 3.6 986S swap (594, 356, 358)

[pkp4911]

Hi, I've posted on another post with someone who had same issues on stock 986S. In the midst of a chicken and egg conundrum because thus far, despite several hundred miles, (not yet 1000 miles since swap completed) I've yet to resolve these codes presenting via info on Durametric.

I have an 03 986S with an 03 M96 3.6 engine swap. Softronic did a 3.6 performance tune on the 986S 7.8 box. Still running stock exhaust but had to create a very basic cold air induction when the shop who did much of the heavy lifting with the swap installed the motor without first mounting the OEM air box/filter. Rather than drop motor again, I created a basic cold air induction set up with cone filter (no oil currently) with a relatively sealed airbox feeding upstream into stock diameter (3") MAF tube with new Bosch MAF in stock location. I also fabricated a mesh inside the tube to emulate the same screen grid/distance from MAF as the factory did.

Both 986 and 996 use same MAF and it is my understanding that MAF is engineered to cope with either 3" diameter or 3.5" from 996. immediately after MAF I coupled and upsized tube diameter via an elbow to 3.5" which ultimately is attached to the stock 996 TB via alum 3.5 tube and elbow. Flow disruption is minimal except for coupler and elbows. I am also utilizing factory 3.6 intake plenum and all vacuum lines were correctly attached.

TB is squeaky clean and my understanding is that the MAF sends its signal based on incoming (pre) air to ECU. Since this is still the 3" diameter, I don't understand why MAF is confused as to tube diameter which is what Softronic suggests...unless the 3.6 tune needs to see 3.5" air flow? (Per the original post, one of the responders mentioned that this can also be tied to fuel in the carbon canister although I don't know how this would occur.)

During swap, we replaced anything we could within reason like OAS, intake gaskets and did a final smoke test to ensure no blatant leaks. Everything went smoothly until we started car and discovered incorrect tune. Immediately started dealing with ECU/MAF issues. I initially had 3 MAF's go on before we could get the car to run and idle smoothly. (Scott forgot I live in Colorado so put a sea level tune on the ECU originally.) Tune is now set for altitude, but I keep getting these codes--and then CEL ultimately trips. Over the course of driving with the Durametric, I also got a code for a bad pre cat 02 sensor so I replaced both at same time. Fact is that the car is not making full power...the 3.2 ran every bit as strong although some of this was initially due to altitude I'm sure.

What am I missing? The only other thought I have is to upsize the incoming diameter pre MAF to 3.5.
The other day I was driving when I came to a stop after sustained highway driving when it died. When I restarted, it ran very rough and would not idle. I was forced to reset but don't remember if the error codes were different. (I think one code mentioned hot film maf...)[IMG][/IMG]
Per the Durametric, here is an example of my readings at idle with oil temp at 84.0C:

Top line Mass air flow (HFM)@23 kg/h

Altitude correction runs between 0.80 and 0.76 ( I live at 8000' but Denver at 5200' value drops the higher I go...)

2nd Mass air flow reading at 22.4 kg/h

02 sensor voltage ahead cat bank 1 matches bank 2 at or around 0.72 with mean values both banks 1.01 and 1.02 What do those mean values represent?

RKAT values close to each other at idle at 0.33%. From 2000 rpm to 4k stays around 0.84% I haven't noticed any gross differences bank to bank (I did when bank 1 o2 sensor failed--like I said, I just replaced both at same time.)

These are random but are they close to normal? Can someone give me normal ranges at 1K RPM increments? Does this apply and what variables exist tied to differences at altitude?

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